To improve the gas mileage of automobiles and the driving characteristics of the automobiles, technologies for providing lightweight wheels have been developed. One of the technologies is to produce wheels using fiber reinforced plastic (hereinafter simply referred to as “FRP”) and, in particular, carbon fiber reinforced plastic (hereinafter simply referred to as “CFRP”) as a material.
For example, Japanese Unexamined Patent Application Publication No. 61-72541 describes a method for manufacturing a disk portion of a wheel by winding a filament-shaped resin-impregnated reinforced fiber around a mandrel (so-called a filament, winding molding method). A device used in the method described in Japanese Unexamined Patent Application Publication No. 61-72541 includes a disk-shaped mandrel, a rotary shaft extending from the central point of the front surface of the mandrel and extending from the central point of the back surface of the mandrel in the perpendicular direction, and a drive unit that rotates the rotary shaft. When a disk portion is produced, the rotary shaft and the mandrel are rotated by the drive unit and, at the same time, a filament is wound around the mandrel while reciprocating from the rotary shaft extending from the front surface and serving as one turning point to the rotary shaft extending from the back surface serving as the other turning point. By stretching a single filament between the front surface and the back surface of the mandrel a plurality of times, a disk portion is finally formed on each of the front surface and the back surface of the mandrel. Thereafter, by bonding the disk portion to an aluminum alloy rim, a wheel is achieved.
Note that by providing a plurality of filaments and stretching each of the filaments between particular locations of the front surface and the back surface of a mandrel using the method described in Japanese Unexamined Patent Application Publication No. 61-72541, a spoke unit of the wheel can be manufactured.